[Illustration: PLATE V. Enteromorpha compressa. Enteromorpha intestinalis. Enteromorpha intestinalis. Anadyomene flabellata.] [Illustration: PLATE VI. Acetabularia crenulata. Dasycladus occidentalis. Penicillus dumentosus. Udotea conglutinata.] GENUS ^Anadyomene^ ^A. flabellata.^ Frond composed entirely of branching filaments, which unite and form an undulating, rigid membranaceous surface, which seems like a network of veins. The species grows in bunches on short stems in the fissures of tidal rocks, and at first view resembles young /Ulva/. It is a very curious and beautiful alga, and should be examined with a glass. It is one inch to four inches in diameter when full-grown. (Plate V.) ORDER =DASYCLADACEÆ= This order also inhabits only tropical or subtropical seas. It is placed in this group, although only the main axis is unicellular. The one-celled axis is surmounted or encircled by whorls of minute filaments or branchlets (/ramuli/), which protrude through small holes and are either persistent or deciduous. In the latter case the fallen filaments leave disk-like scars on the stem. GENUS ^Acetabularia^ ^A. crenulata.^ This little alga resembles a mushroom of the /Agaricus/ variety or gilled species, and so is easily identified. It is thinly incrusted with lime and is found on rocks and coral, within tide-marks, on the Florida reefs. When full-grown the stipe is two to three inches long and the cap one half of an inch in diameter. (Plate VI.) GENUS ^Dasycladus^ Fronds destitute of calcareous matter, soft, cylindrical or club-shaped; single unicellular axis, beset with fine filaments or ramuli. ^D. occidentalis.^ Frond club-shaped, one to two inches high, one half of an inch or less in diameter; covered with whorls of fine filaments, making the fronds almost spongy; substance soft but tough; dark green. These plants have been compared to foxes' tails. They grow in bunches on rocks between tide-marks. (Plate VI.) GENUS ^Cymopolia^ ^C. barbata.^ Frond branched, dividing regularly in pairs; thickly incrusted with lime. Annular constrictions at short intervals give the branches the appearance of strings of beads. Each section is covered with pores or scars of fallen ramuli. The branches terminate in tufts of fine filaments. [pg058] ORDER =UDOTEACEÆ= GENUS ^Penicillus^ The merman's shaving-brush, characteristic of coral reefs. ^P. dumentosus.^ Holdfast much branched, like a fibrous root, and penetrating deep into the coral or sand; stem short, thick, more or less flattened, sometimes hollow, covered with velvety scurf; top covered with loosely spreading tuft of soft filaments three to six inches long, which branch repeatedly in pairs (dichotomous); color deep green. When old, these plants are incrusted with a thin, porous layer of carbonate of lime. (Plate VI.)